U.S. patent application number 12/145577 was filed with the patent office on 2008-10-09 for peer to peer (p2p) federated concept queries.
Invention is credited to Richard D. Dettinger, Frederick A. Kulack.
Application Number | 20080250005 12/145577 |
Document ID | / |
Family ID | 39827866 |
Filed Date | 2008-10-09 |
United States Patent
Application |
20080250005 |
Kind Code |
A1 |
Dettinger; Richard D. ; et
al. |
October 9, 2008 |
PEER TO PEER (P2P) FEDERATED CONCEPT QUERIES
Abstract
Embodiments of the invention are generally related to data
processing, and more specifically to retrieving results for a query
from one or more devices coupled to a network. A first device may
receive an abstract query including logical fields defined by a
first data abstraction model and retrieve query results stored in
the first device. The query may be sent to one or more other
devices via the network. The one or more other devices may be
configured to convert the abstract query to local abstract queries
including logical fields defined in local data abstraction models.
The local queries may be issued against local databases to retrieve
additional results for the query.
Inventors: |
Dettinger; Richard D.;
(Rochester, MN) ; Kulack; Frederick A.;
(Rochester, MN) |
Correspondence
Address: |
IBM CORPORATION, INTELLECTUAL PROPERTY LAW;DEPT 917, BLDG. 006-1
3605 HIGHWAY 52 NORTH
ROCHESTER
MN
55901-7829
US
|
Family ID: |
39827866 |
Appl. No.: |
12/145577 |
Filed: |
June 25, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11226181 |
Sep 14, 2005 |
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12145577 |
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10083075 |
Feb 26, 2002 |
6996558 |
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11226181 |
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Current U.S.
Class: |
1/1 ;
707/999.004; 707/E17.005; 707/E17.014; 707/E17.032;
707/E17.135 |
Current CPC
Class: |
G06F 16/256 20190101;
G06F 16/903 20190101 |
Class at
Publication: |
707/4 ;
707/E17.014; 707/E17.005 |
International
Class: |
G06F 7/10 20060101
G06F007/10; G06F 17/30 20060101 G06F017/30 |
Claims
1. A method for retrieving query results comprising: receiving an
abstract query from a requesting entity, wherein the abstract query
comprises one or more logical fields defined in a first data
abstraction model comprising a plurality of first logical field
definitions mapping the first logical fields to physical fields of
a first database in a first device coupled to a network; issuing
the abstract query against the database to retrieve a first set of
results for the abstract query; sending the abstract query to at
least one second device coupled to the network, the second device
comprising a second data abstraction model comprising a plurality
of second logical field definitions mapping the second logical
fields to physical fields of a second database, wherein the second
logical fields are distinct from the first logical fields;
receiving a second set of results for the abstract query from the
at least one second device; and providing the first and second set
of results to the requesting entity.
2. The method of claim 1, wherein the abstract query comprises a
concept code associated with each of the one or more logical fields
of the abstract query, wherein the concept code associates a
respective logical field to standardized metadata describing the
logical field.
3. The method of claim 1, wherein the network is a peer-to-peer
network.
4. The method of claim 1, further comprising concatenating the
first set of results and second set of results prior to providing
the first and second set of results to the requesting entity.
5. The method of claim 1, further comprising performing a union
operation to combine the first set of results and the second set of
results prior to providing the first and second set of results to
the requesting entity.
6. The method of claim 1, wherein the requesting entity is one of a
client computer and an application.
7. The memory circuit of claim 1, wherein the first device and
second device are servers.
8. A computer readable storage medium comprising a program product
which, when executed by a processor is configured to perform an
operation for retrieving query results, comprising: receiving an
abstract query from a requesting entity, wherein the abstract query
comprises one or more logical fields defined in a first data
abstraction model comprising a plurality of first logical field
definitions mapping the first logical fields to physical fields of
a first database in a first device coupled to a network; issuing
the abstract query against the database to retrieve a first set of
results for the abstract query; sending the abstract query to at
least one second device coupled to the network, the second device
comprising a second data abstraction model comprising a plurality
of second logical field definitions mapping the second logical
fields to physical fields of a second database, wherein the second
logical fields are distinct from the first logical fields;
receiving a second set of results for the abstract query from the
at least one second device; and providing the first and second set
of results to the requesting entity.
9. The computer readable storage medium of claim 8, wherein the
abstract query comprises a concept code associated with each of the
one or more logical fields of the abstract query, wherein the
concept code associates a respective logical field to standardized
metadata describing the logical field.
10. The computer readable storage medium of claim 8, wherein the
network is a peer-to-peer network.
11. The computer readable storage medium of claim 8, wherein the
operation further comprises concatenating the first set of results
and second set of results prior to providing the first and second
set of results to the requesting entity.
12. The computer readable storage medium of claim 8, wherein the
operation further comprises performing a union operation to combine
the first set of results and the second set of results prior to
providing the first and second set of results to the requesting
entity.
13. The computer readable storage medium of claim 8, wherein the
requesting entity is one of a client computer and an
application.
14. The computer readable storage medium of claim 8, wherein the
first device and second device are servers.
15. A system, comprising a plurality of devices coupled via a
network, wherein each device is configured to: receive an abstract
query from a requesting entity, wherein the abstract query
comprises one or more logical fields defined in a first data
abstraction model comprising a plurality of first logical field
definitions mapping the first logical fields to physical fields of
a first database; issue the abstract query against the database to
retrieve a first set of results for the abstract query; send the
abstract query to at least one other device coupled to the network,
the at least one other device comprising a second data abstraction
model comprising a plurality of second logical field definitions
mapping the second logical fields to physical fields of a second
database, wherein the second logical fields are distinct from the
first logical fields; receive a second set of results for the
abstract query from the at least one other device; and provide the
first and second set of results to the requesting entity.
16. The system of claim 15, wherein the abstract query comprises a
concept code associated with each of the one or more logical fields
of the abstract query, wherein the concept code associates a
respective logical field to standardized metadata describing the
logical field.
17. The system of claim 15, wherein the network is a peer-to-peer
network.
18. The system of claim 15, wherein each device is further
configured to concatenate the first set of results and second set
of results prior to providing the first and second set of results
to the requesting entity.
19. The system of claim 15, wherein each device is further
configured to perform a union operation to combine the first set of
results and the second set of results prior to providing the first
and second set of results to the requesting entity.
20. The system of claim 15, wherein the requesting entity is one of
a client computer and an application.
21. The system of claim 15, wherein the plurality of devices are
servers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. patent application Ser. No. 11/226,181, filed Sep. 14.sup.th,
2005, which is a continuation of U.S. Pat. No. 6,996,558, filed
Feb. 26.sup.th, 2002. Each of the aforementioned related patent
applications is herein incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is generally related to data
processing, and more specifically to retrieving data from a
database.
[0004] 2. Description of the Related Art
[0005] Databases are computerized information storage and retrieval
systems. A relational database management system is a computer
database management system (DBMS) that uses relational techniques
for storing and retrieving data. The most prevalent type of
database is the relational database, a tabular database in which
data is defined so that it can be reorganized and accessed in a
number of different ways. A distributed database is one that can be
dispersed or replicated among different points in a network. An
object-oriented programming database is one that is congruent with
the data defined in object classes and subclasses.
[0006] Regardless of the particular architecture, in a DBMS, a
requesting entity (e.g., an application or the operating system)
demands access to a specified database by issuing a database access
request. Such requests may include, for instance, simple catalog
lookup requests or transactions and combinations of transactions
that operate to read, change and add specified records in the
database. These requests are made using high-level query languages
such as the Structured Query Language (SQL) and application
programming interfaces (API's) such as Java.RTM. Database
Connectivity (JDBC). The term "query" denominates a set of commands
for retrieving data from a stored database. Queries take the form
of a command language, such as SQL, that lets programmers and
programs select, insert, update, find the location of data, and so
forth.
[0007] Any requesting entity, including applications, operating
systems and, at the highest level, users, can issue queries against
data in a database. Queries may be predefined (i.e., hard coded as
part of an application) or may be generated in response to input
(e.g., user input). Upon execution of a query against a database, a
query result is returned to the requesting entity.
SUMMARY OF THE INVENTION
[0008] The present invention is generally related to data
processing, and more specifically to retrieving data from a
database.
[0009] One embodiment of the invention provides a method for
retrieving query results. The method generally comprises receiving
an abstract query from a requesting entity, wherein the abstract
query comprises one or more logical fields defined in a first data
abstraction model comprising a plurality of first logical field
definitions mapping the first logical fields to physical fields of
a first database in a first device coupled to a network and issuing
the abstract query against the database to retrieve a first set of
results for the abstract query. The method further comprises
sending the abstract query to at least one second device coupled to
the network, the second device comprising a second data abstraction
model comprising a plurality of second logical field definitions
mapping the second logical fields to physical fields of a second
database, wherein the second logical fields are distinct from the
first logical fields, receiving a second set of results for the
abstract query from the at least one second device, and providing
the first and second set of results to the requesting entity.
[0010] Another embodiment of the invention provides a computer
readable storage medium comprising a program product which, when
executed by a processor is configured to perform an operation for
retrieving query results. The operation generally comprises
receiving an abstract query from a requesting entity, wherein the
abstract query comprises one or more logical fields defined in a
first data abstraction model comprising a plurality of first
logical field definitions mapping the first logical fields to
physical fields of a first database in a first device coupled to a
network and issuing the abstract query against the database to
retrieve a first set of results for the abstract query. The
operation further comprises sending the abstract query to at least
one second device coupled to the network, the second device
comprising a second data abstraction model comprising a plurality
of second logical field definitions mapping the second logical
fields to physical fields of a second database, wherein the second
logical fields are distinct from the first logical fields,
receiving a second set of results for the abstract query from the
at least one second device, and providing the first and second set
of results to the requesting entity.
[0011] Yet another embodiment of the invention provides a system,
generally comprising a plurality of devices coupled via a network,
wherein each device is configured to receive an abstract query from
a requesting entity, wherein the abstract query comprises one or
more logical fields defined in a first data abstraction model
comprising a plurality of first logical field definitions mapping
the first logical fields to physical fields of a first database and
issue the abstract query against the database to retrieve a first
set of results for the abstract query. Each device is further
configured to send the abstract query to at least one other device
coupled to the network, the at least one other device comprising a
second data abstraction model comprising a plurality of second
logical field definitions mapping the second logical fields to
physical fields of a second database, wherein the second logical
fields are distinct from the first logical fields, receive a second
set of results for the abstract query from the at least one other
device, and provide the first and second set of results to the
requesting entity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features,
advantages and objects of the present invention are attained and
can be understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to the
embodiments thereof which are illustrated in the appended
drawings.
[0013] It is to be noted, however, that the appended drawings
illustrate only typical embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0014] FIG. 1 illustrates an exemplary system according to an
embodiment of the invention.
[0015] FIG. 2 illustrates a more detailed view of an exemplary
client computer and server, according to an embodiment of the
invention.
[0016] FIG. 3 illustrates an exemplary relational view 300 of
system components according to an embodiment of the invention.
[0017] FIG. 4 illustrates a data abstraction model according to an
embodiment of the invention.
[0018] FIG. 5 illustrates query execution in an exemplary system
according to an embodiment of the invention.
[0019] FIG. 6 illustrates query execution in another exemplary
system according to an embodiment of the invention.
[0020] FIG. 7 is a flow diagram of exemplary operations performed
by a query manager according to an embodiment of the invention.
[0021] FIG. 8 is another flow diagram of exemplary operations
performed by a query manager according to an embodiment of the
invention.
[0022] FIG. 9 illustrates an exemplary structure defining
relationships between concepts.
[0023] FIG. 10 is a flow diagram of exemplary operations performed
to provide metadata regarding concepts and logical fields,
according to an embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Embodiments of the invention are generally related to data
processing, and more specifically to retrieving results for a query
from one or more devices coupled to a network. A first device may
receive an abstract query including logical fields defined by a
first data abstraction model and retrieve query results stored in
the first device. The query may be sent to one or more other
devices via the network. The one or more other devices may be
configured to convert the abstract query to local abstract queries
including logical fields defined in local data abstraction models.
The local queries may be issued against local databases to retrieve
additional results for the query.
[0025] In the following, reference is made to embodiments of the
invention. However, it should be understood that the invention is
not limited to specific described embodiments. Instead, any
combination of the following features and elements, whether related
to different embodiments or not, is contemplated to implement and
practice the invention. Furthermore, in various embodiments the
invention provides numerous advantages over the prior art. However,
although embodiments of the invention may achieve advantages over
other possible solutions and/or over the prior art, whether or not
a particular advantage is achieved by a given embodiment is not
limiting of the invention. Thus, the following aspects, features,
embodiments and advantages are merely illustrative and are not
considered elements or limitations of the appended claims except
where explicitly recited in a claim(s). Likewise, reference to "the
invention" shall not be construed as a generalization of any
inventive subject matter disclosed herein and shall not be
considered to be an element or limitation of the appended claims
except where explicitly recited in a claim(s).
[0026] One embodiment of the invention is implemented as a program
product for use with a computer system. The program(s) of the
program product defines functions of the embodiments (including the
methods described herein) and can be contained on a variety of
computer-readable storage media. Illustrative computer-readable
storage media include, but are not limited to: (i) non-writable
storage media (e.g., read-only memory devices within a computer
such as CD-ROM disks readable by a CD-ROM drive) on which
information is permanently stored; (ii) writable storage media
(e.g., floppy disks within a diskette drive or hard-disk drive) on
which alterable information is stored. Such computer-readable
storage media, when carrying computer-readable instructions that
direct the functions of the present invention, are embodiments of
the present invention. Other media include communications media
through which information is conveyed to a computer, such as
through a computer or telephone network, including wireless
communications networks. The latter embodiment specifically
includes transmitting information to/from the Internet and other
networks. Such communications media, when carrying
computer-readable instructions that direct the functions of the
present invention, are embodiments of the present invention.
Broadly, computer-readable storage media and communications media
may be referred to herein as computer-readable media.
[0027] In general, the routines executed to implement the
embodiments of the invention, may be part of an operating system or
a specific application, component, program, module, object, or
sequence of instructions. The computer program of the present
invention typically is comprised of a multitude of instructions
that will be translated by the native computer into a
machine-readable format and hence executable instructions. Also,
programs are comprised of variables and data structures that either
reside locally to the program or are found in memory or on storage
devices. In addition, various programs described hereinafter may be
identified based upon the application for which they are
implemented in a specific embodiment of the invention. However, it
should be appreciated that any particular program nomenclature that
follows is used merely for convenience, and thus the invention
should not be limited to use solely in any specific application
identified and/or implied by such nomenclature.
EXEMPLARY SYSTEM
[0028] FIG. 1 depicts a block diagram of a networked system 100 in
which embodiments of the invention may be implemented. In general,
the networked system 100 includes at least one client (e.g.,
user's) computer 101 and a plurality of servers 102 (four such
servers 102a-d shown). The client computer 101 may be coupled with
a server 102 (server 102a in FIG. 1) via a network 140. In general,
the network 140 may be a local area network (LAN) and/or a wide
area network (WAN). In a particular embodiment, the network 140 is
the Internet. In one embodiment, the client computer 101 may be
configured to issue queries against the server 102a and retrieve
data from the server 102a, as will be described in greater detail
below.
[0029] Each of the servers 102 may be coupled with each other via a
network 190. Like network 140, network 190 may also be any one of
140 may be any one or a local area network (LAN), a wide area
network (WAN), and/or the Internet. In a particular embodiment of
the invention the network 190 may be a peer-to-peer network. A
peer-to-peer network is defined herein as any network comprising
two or more interconnected devices that are configured to share
their respective data, resources, and the like. The devices
associated with network 190 may be coupled in any reasonable
manner, whether known or unknown, to form any type of P2P network.
Exemplary P2P network types include centralized P2P network,
decentralized P2P network, structured P2P network, unstructured P2P
network, hybrid P2P network, and the like.
[0030] Regardless of the type of P2P network 190, generally, any
server 102 connected to the P2P network 190 may be configured to
independently collect, store, analyze and modify data. Furthermore,
the data stored on any server 102 may be transferred to any other
server 102 via the network 190. For example, in one embodiment,
each server 102 may be configured to issue queries to one or more
other servers 102 via the network 190 to retrieve desired data.
[0031] While two separate networks 140 and 190 are illustrated in
FIG. 1, in alternative embodiments, client computers 101 and the
servers 102 may be coupled to the same network, for example, the
Internet.
[0032] In one embodiment of the invention, in response to receiving
a query from the client computer 101, server 102a may be configured
to retrieve query results that are stored therein. The server 102a
may also be configured to transfer the query to one or more other
servers 102 via the network 190, retrieve further query results
stored in the one or more other server 102, and provide the query
results to the client computer 101. Retrieving query results from
one or more servers 102 coupled with the P2P network 190 is
described in greater detail below.
[0033] FIG. 2 illustrates a more detailed view of an exemplary
client computer 101 and a server 102, according to an embodiment of
the invention. The server 102 may be any one or servers 102a-d
depicted in FIG. 1. The client computer 101 may include a Central
Processing Unit (CPU) 211 connected via a bus 220 to a memory 212,
storage 216, an input device 217, an output device 218, and a
network interface device 219. The input device 217 can be any
device to give input to the client computer 101. For example, a
keyboard, keypad, light-pen, touch-screen, track-ball, or speech
recognition unit, audio/video player, and the like could be used.
The output device 218 can be any device to give output to the user,
e.g., any conventional display screen. Although shown separately
from the input device 217, the output device 218 and input device
217 could be combined. For example, a display screen with an
integrated touch-screen, a display with an integrated keyboard, or
a speech recognition unit combined with a text speech converter
could be used.
[0034] The network interface device 219 may be any entry/exit
device configured to allow network communications between the
client computers 101 and server 102 via the network 140. For
example, the network interface device 219 may be a network adapter
or other network interface card (NIC).
[0035] Storage 216 is preferably a Direct Access Storage Device
(DASD). Although it is shown as a single unit, it could be a
combination of fixed and/or removable storage devices, such as
fixed disc drives, floppy disc drives, tape drives, removable
memory cards, or optical storage. The memory 212 and storage 216
could be part of one virtual address space spanning multiple
primary and secondary storage devices.
[0036] The memory 212 is preferably a random access memory
sufficiently large to hold the necessary programming and data
structures of the invention. While memory 212 is shown as a single
entity, it should be understood that memory 212 may in fact
comprise a plurality of modules, and that memory 212 may exist at
multiple levels, from high speed registers and caches to lower
speed but larger DRAM chips.
[0037] Illustratively, the memory 212 contains an operating system
213. Illustrative operating systems, which may be used to
advantage, include Linux (Linux is a trademark of Linus Torvalds in
the US, other countries, or both) and Microsoft's Windows.RTM..
More generally, any operating system supporting the functions
disclosed herein may be used.
[0038] Memory 212 is also shown containing a query program 114
which, when executed by CPU 211, provides support for issuing
queries to server 102. In one embodiment, the query program 214 may
include a web-based Graphical User Interface (GUI), which allows
the user to display Hyper Text Markup Language (HTML) information.
The GUI may be configured to allow a user to create a query, issue
the query against a server 102, and display the results of the
query. More generally, however, the query program may be a
GUI-based program capable of rendering any information transferred
between the client computer 101 and the server 102.
[0039] The server 102 may be physically arranged in a manner
similar to the client computer 101. Accordingly, the server 102 is
shown generally comprising a CPU 221, memory 222, and a storage
device 226, coupled with one another by a bus 130. Memory 222 may
be a random access memory sufficiently large to hold the necessary
programming and data structures that are located on server 102.
[0040] The server 102 may generally be under the control of an
operating system 223 shown residing in memory 222. Examples of the
operating system 123 include IBM OS/400.RTM., UNIX, Microsoft
Windows.RTM., Linux and the like. More generally, any operating
system capable of supporting the functions described herein may be
used.
[0041] The memory 222 may further include one or more applications
240 and an abstract query interface 246. The applications 240 and
the abstract query interface 246 may be software products
comprising a plurality of instructions that are resident at various
times in various memory and storage devices in the computer system
100. When read and executed by a processor 221 in the server 102,
the applications 240 and the abstract query interface 246 cause the
computer system 100 to perform the steps necessary to execute steps
or elements embodying the various aspects of the invention.
[0042] The applications 240 (and more generally, any requesting
entity, including the operating system 223) may be configured to
issue queries against a database 227 (shown in storage 226). The
database 227 is representative of any collection of data regardless
of the particular physical representation. By way of illustration,
the database 227 may be organized according to a relational schema
(accessible by SQL queries) or according to an XML schema
(accessible by XML queries). However, the invention is not limited
to a particular schema and contemplates extension to schemas
presently unknown. As used herein, the term "schema" generically
refers to a particular arrangement of data.
[0043] In one embodiment, the queries issued by the applications
240 are defined according to an application query specification 242
included with each application 240. The queries issued by the
applications 240 may be predefined (i.e., hard coded as part of the
applications 240) or may be generated in response to input (e.g.,
user input). In either case, the queries (referred to herein as
"abstract queries") are composed using logical fields defined by
the abstract query interface 246. In particular, the logical fields
used in the abstract queries are defined by a data abstraction
model 248 of the abstract query interface 246. The abstract queries
are executed by a runtime component 250 which transforms the
abstract queries into a form consistent with the physical
representation of the data contained in the database 227. The
application query specification 242 and the abstract query
interface 246 are further described with reference to FIG. 3.
[0044] The applications 240 may also include a query manager
program 244. Query manager 244 may be configured to receive a query
from a client computer 101, or an application 240, receive results
for the query, and provide the query results to the requesting
client computer 101 or application 240. In one embodiment of the
invention retrieving query results may involve retrieving query
results from the database 227, as described above. In some
embodiments, the query manager 244 may be configured to transfer a
received query to one or more other servers 102 via the P2P network
190, and retrieve query results from the one or more other servers
102, as will be discussed in greater detail below.
RELATIONAL VIEW OF ENVIRONMENT
[0045] FIG. 3 illustrates an exemplary relational view 300 of
components according to an embodiment of the invention. A
requesting entity, for example, an application 240 may issue a
query 302 as defined by the respective application query
specification 242 of the requesting entity. The resulting query 302
is generally referred to herein as an "abstract query" because the
query is composed according to abstract (i.e., logical) fields
rather than by direct reference to the underlying physical data
entities in the database 227. As a result, abstract queries may be
defined that are independent of the particular underlying data
representation used. In one embodiment, the application query
specification 242 may include both criteria used for data selection
and an explicit specification of the fields to be returned based on
the selection criteria.
[0046] The logical fields specified by the application query
specification 242 and used to compose the abstract query 302 may be
defined by the data abstraction model 248. In general, the data
abstraction model 248 may expose information as a set of logical
fields that may be used within a query (e.g., the abstract query
302) issued by the application 240 to specify criteria for data
selection and specify the form of result data returned from a query
operation. The logical fields may be defined independently of the
underlying data representation being used in the database 227,
thereby allowing queries to be formed that are loosely coupled to
the underlying data representation. Abstract queries are described
in greater detail in co-pending U.S. patent application Ser. No.
11/226,181, entitled IMPROVED APPLICATION PORTABILITY AND
EXTENSIBILITY THROUGH DATABASE SCHEMA AND QUERY ABSTRACTION, filed
Sep. 14.sup.th, 2005, which is incorporated herein by reference in
its entirety.
[0047] FIG. 4 illustrates an exemplary data abstraction 148 model
according to an embodiment of the invention. In general, data
abstraction model 148 comprises a plurality of field specifications
408. A field specification may be provided for each logical field
available for composition of an abstract query. Each field
specification may comprise a logical field name 410 and access
method 412. For example, the field specification for Field A in
FIG. 3 includes a logical field name 410a (`LastName`), and an
associated access method 412a (`simple`).
[0048] The access methods may associate logical field names 410 to
a particular physical data representation 314 (See FIG. 3) in a
database 227. By way of illustration, two data representations are
shown in FIG. 3, an XML data representation 314.sub.1, and a
relational data representation 314.sub.2. However, the physical
data representation 314.sub.N indicates that any other data
representation, known or unknown, is contemplated. In one
embodiment, a single data abstraction model 148 may contain field
specifications with associated access methods for two or more
physical data representations 314. In an alternative embodiment, a
separate data abstraction model 148 may be provided for each
separate data representation 314.
[0049] Any number of access method types is contemplated depending
upon the number of different types of logical fields to be
supported. In one embodiment, access methods for simple fields,
filtered fields and composed fields are provided. For example,
field specifications for Field A exemplify a simple field access
method 412a. Simple fields are mapped directly to a particular
entity in the underlying physical data representation (e.g., a
field mapped to a given database table and column). By way of
illustration, the simple field access method 412a, shown in FIG. 4
maps the logical field name 410a (`LastName`) to a column named
"I_name" in a table named "Test Table," as illustrated.
[0050] The field specification for Field X exemplifies a filtered
field access method 412b. Filtered fields identify an associated
physical entity and provide rules used to define a particular
subset of items within the physical data representation. For
example, the filtered field access method 412b may map the logical
field name 410b to a physical entity in a column named "TestVal" in
a table named "Test Table" and may define a filter for the test
values. For example, in one embodiment, the filter may define a
numerical range in which the test values may be deemed valid.
[0051] A composed field access method may also be provided to
compute a logical field from one or more physical fields using an
expression supplied as part of the access method definition. In
this way, information which does not exist in the underlying data
representation may be computed. For example, a sales tax field may
be composed by multiplying a sales price field by a sales tax
rate.
[0052] It is contemplated that the formats for any given data type
(e.g., dates, decimal numbers, etc.) of the underlying data may
vary. Accordingly, in one embodiment, the field specifications 408
may include a type attribute which reflects the format of the
underlying data. However, in another embodiment, the data format of
the field specifications 408 is different from the associated
underlying physical data, in which case an access method is
responsible for returning data in the proper format assumed by the
requesting entity.
[0053] Thus, the access method must know what format of data is
assumed (i.e., according to the logical field) as well as the
actual format of the underlying physical data. The access method
may then convert the underlying physical data into the format of
the logical field. By way of example, the field specifications 408
of the data abstraction model 248 shown in FIG. 3 are
representative of logical fields mapped to data represented in the
relational data representation 314.sub.2. However, other instances
of the data abstraction model 248 map logical fields to other
physical data representations, such as XML.
[0054] Each field 408 of the data abstraction model 148 may also
include a concept code 409. For example, the concept code for field
408a may be 101 as illustrated in FIG. 4. Concept code 409 may
associate a respective field 408 to a predefined universal concept.
For example, field 408a illustrated in FIG. 4 is associated with a
column containing last names. Accordingly, field 408a is titled
"Last Name" and associated with the column "I_name" in the table
"Test Table". However, the concept "last name" may have several
synonyms. For example, in some systems last names may be identified
as a "surnames" or "family names". The concept code 409 may provide
a means for identifying a universal concept, regardless of how it
is specifically labeled in a given system. Accordingly, concept
codes may also be referred to herein as "entity resolution
attributes" in that these attributes are applied to resolve one
local field definition (for a first data abstraction model) to
another local field definition (for a second data abstraction
model) on the basis of a standardized field definition.
[0055] For example, referring to FIG. 1, the data abstraction model
in server 102a may have a logical field named "Last Name" and the
data abstraction model in server 102b may have a logical field
named "Family Name". The concept code for the field "Last Name" in
server 102a and the concept code for the field "Family Name" in
server 102b may both be 101 because they both refer to the same
concept.
[0056] While a numerical concept code 409 is illustrated in FIG. 4,
in alternative embodiments any combination of alphabets, numbers,
words, phrases, symbols, and the like may be used to define concept
codes. In one embodiment of the invention, the concept code 409 may
be derived from a recognized universal vocabulary, such as, for
example, a standardized industry-specific vocabulary. Exemplary
standardized universal vocabularies may include, among others, UMLS
(Universal Medical Language System), MeSH (Medical Subject
Headings), SnoMed (Systematic Nomenclature of Medicine), and the
like.
[0057] Furthermore, while standardized universal vocabularies are
described herein with reference to concept codes 409, in
alternative embodiments, the concept codes 409 may be generated for
internal use by groups of individuals and/or organizations. For
example, while working on a project, one or more entities working
on the project may agree upon a standardized set on concepts and
respective concept codes for categorizing data. Thereafter, each
entity may then generate their own respective data abstraction
models to store data related to their respective project tasks in
their own respective server or system. The data abstraction model
generated by each entity may be different. For example, each entity
may define its own logical fields in a respective data abstraction
model which may be distinct from the logical fields defined by
other entities. However, the concept codes used to define fields in
the respective data abstraction models may be derived from the
agreed upon set of concept codes.
RETRIEVING RESULTS FROM MULTIPLE PEER DEVICES
[0058] In one embodiment of the invention, the concept codes may
facilitate retrieving query results from a plurality of devices in
a P2P network. FIG. 5 illustrates another exemplary system 500
according to an embodiment of the invention. System 500 may be
similar to system 100 illustrated in FIG. 1, and therefore may
include at least one client computer 101 and a plurality of servers
102, for example, servers 102a-d coupled to each other via the P2P
network 190. As illustrated in FIG. 5, each of the servers 102a-d
may include a respective data abstraction model 248a-d. The data
abstraction models 248a-d may define logical fields that may be
used to compose abstract queries that may be issued against
databases in respective servers 102a-d.
[0059] In one embodiment of the invention, the servers 102a-d may
be peer devices operated by entities working on a collaborative
project. For example, in a particular embodiment, each of the
servers 102a-d may be associated with a respective university for
storing research data. In alternative embodiments, each of the
servers 102a-d may belong to a respective hospital or a department
of a hospital, wherein each server 102 stores patient records,
medical research data, and the like. More generally, each of the
servers 102a-d may belong to one or more entities, whether
individuals or organizations, that collect and store data in an
independent and decentralized manner.
[0060] A decentralized approach to collecting and storing data may
be advantageous because it may allow each entity to collect and
store the data without being subject to each others' data
collection procedures, data categorizations, analysis and the like.
Therefore, the decentralized data collection and storing methods
may facilitate a wide variety of entities to be seamlessly
integrated into a collaborative project.
[0061] However, the independent data collection and storage may
also result in difficulties while sharing data between the
entities. For example, while performing research on a particular
disease, a hospital or university may desire data collected by one
or more other hospitals and/or universities to aid the research.
However, different categorization of data in each hospital or
university server may make it difficult to retrieve such data. For
example, as described above, the DAM 248a may have a logical field
named "Last Name" and DAM 248b may have a logical field named
"Family Name". Furthermore, the DAM 248c may have a logical field
named "Surname". Therefore, retrieving data related to last names
from servers 102a-c may require separate abstract queries to be
written for each of the servers 102a-c. Manually writing multiple
abstract queries and combining the query results may be a tedious,
inefficient and error prone process.
[0062] In one embodiment of the invention, the fields in the data
abstraction models 248a-d may have similar concepts but may have
varying logical field definitions. Embodiments of the invention
provide an automated method for retrieving query results from a
plurality of servers 102 coupled to a P2P network 109 using concept
codes in response to receiving a query. For example, as illustrated
in FIG. 5, an abstract query 510 may be sent from a client computer
101 to server 102a. Alternatively an application program 240 of
server 102a (see FIG. 2) may generate an abstract query 510. The
query 510 may be received by the query manager 244a of the server
102a. Query manager 244a may issue the abstract query 510 against a
database associated with server 102a to retrieve at least some of
the results of the query.
[0063] Furthermore, the query manager 244a may send the abstract
query 510 to one or more of the servers 102b-d to request further
results for the abstract query 510, as illustrated in FIG. 5. For
example, in one embodiment, the server 102a may include a record
including a list of the peer computers 102b-d. Accordingly, the
query manager 244a may be configured to access the record to
determine peer computers prior to sending the abstract query 510 to
the peer servers 102b-d. In one embodiment, the query manager 244a
may send the abstract query 510 to all known peers servers.
Alternatively, in some embodiment, the query manager 244a may send
the abstract query 510 to a subset of the known peers.
[0064] The abstract query 510 may be received by each of query
managers 244b-d at the servers 102b-d. Each of the query managers
244b-d may convert the abstract query 510 to a local abstract query
based on concept codes as will be described in greater detail
below. The query managers 244b-d may issue the local abstract
queries against respective databases associated with the servers
102b-d to retrieve further results for the abstract query 510.
[0065] In one embodiment, the query results from each of the
servers 102b-d may be transferred to the server 102a via the P2P
network 190, as illustrated in FIG. 5. The query results from each
of the servers 102b-d may be received by the query manager 244a. In
one embodiment, the query manager 244a may combine the results
received from the servers 102b-d with the query results retrieved
from the server 102a and provide the results to a requesting client
101 or application program 240. Alternatively, the query manager
may be configured to average and/or normalize the set of results
received from the server 102a-d.
[0066] In some embodiments, the abstract query 510 may include one
or more clauses that determine how query results are to be
presented. For example, in a particular embodiment, the abstract
query 510 may include a sort clause that, for example, requires
that query results be presented in an ascending or descending order
in relation to a particular results field. Accordingly, in some
embodiments, the query manager 244a may be configured to perform
one or more operations, for example, sorting, on the combined
result set prior to presenting the query results to a requesting
entity. In some embodiments, the query manager 244a may be
configured to provide source identification data of the query
results to a requesting entity. For example, the query manager 244a
may be configured to identify the particular server 102a-d from
which a particular query result is derived. The identification data
may be displayed in an identification field that may be included in
the query results.
[0067] In one embodiment of the invention, the abstract query 510
received by server 102 from a client 101 or an application program
240 of server 102a may include logical fields defined by the
abstraction model 248a of server 102a. An exemplary abstract query
510 is provided below: [0068] SELECT First Name [0069] WHERE Last
Name="Smith"
[0070] The abstract query 510 provided above may be configured to
retrieve first names of individuals whose last name is "Smith".
Illustratively, the fields "First Name" and "Last Name" may be
logical fields defined by the data abstraction model 248a of server
102a.
[0071] In one embodiment of the invention, abstract query 510 may
be transferred to the one or more other servers 102b-d by query
manager 244aalong with concept codes associated with each logical
field of the abstract query 510. In one embodiment, the concept
codes may be encoded into the abstract query 510. For example, the
query manager 244a may transfer the concept codes for "Last Name"
and "First Name" along with the abstract query 510 provided above
to the one or more other servers 102b-d.
[0072] Upon receiving the abstract query 510 from server 102a, each
of the one or more query managers 244b-d may be configured to
convert the abstract query 510 to a local abstract query based on
the concept codes associated with each logical field of abstract
query 510. For example, the DAM 248b of server 102b may include the
logical fields "Family Name" and "Given Name". The concept codes
associated with the logical fields "Last Name" and "First Name" of
DAM 248a of server 102a may be the same as the concept codes
associated with the logical fields "Family Name" and "Given Name"
of DAM 248b of server 102b. Accordingly, the query manager 244b of
server 102b may be configured to generate the following local
abstract query upon receiving the abstract query 510 provided
above: [0073] SELECT Given Name [0074] WHERE Family
Name="Smith"
[0075] Local abstract queries may be similarly generated at each of
the servers 102 receiving the abstract query 510 to retrieve
results. The results may then be transferred to the server 102a via
the network 190. Upon receiving the query results from the server
102a and one or more other servers 102b-d, query program 244a of
server 102 may provide the results to a requesting client computer
101 or application 240.
[0076] In one embodiment of the invention, providing the results to
a requesting client computer or application may involve performing
a union operation to combine results received from each server
102a-d. However, any other reasonable method of integrating results
received from multiple sources, for example, concatenation, may be
also used. In alternative embodiments, the results from each source
may be provided separately, for example, in separate files, or
separated within a given results file. In one embodiment, the
results from each of the servers 102 may be displayed in a GUI
screen at the client computer 101.
[0077] In one embodiment of the invention, one or more servers 102
may receive the query 510, but may not have any results for the
query. For example, server 102d may receive abstract query 510
described above, but may not have a logical field corresponding to
the concept code of "Last Name". Accordingly, the server 102d may
be configured to respond to the server 102 with a "No result" or
error message.
[0078] In one embodiment of the invention, the query manager 244a
of server 102a may be configured to wait until results (or other
response) are received from each of the one or more servers 102b-d
before providing the query results to the requesting client
computer 101 or application 240. In alternative embodiment, query
manager 244a may wait for a predefined period of time to receive
results. If the results are not received from all servers 102
within the predefined period of time, the query program 244a may be
configured to provide only results received within the predefined
period of time.
[0079] For purposes of illustration only, FIG. 5 shows the query
510 being sent from server 102a to each of the servers 102b-d.
However, more generally, the query 510 may be sent from any server
102, to any one or more other servers 102 coupled to the P2P
network 190. For example, each of the servers 102 of FIG. 5 may be
configured to receive abstract queries from respective client
computers 101 or application programs 240 and send the query to one
or more other servers 102 as described above. Furthermore, in some
embodiments the client computer 101 may be directly coupled with
the P2P network 190 and configured to issue a query 510 to one or
more servers 102. Accordingly, in some embodiments, the client
computer 101 may include similar components as the servers 102, for
example, a data abstraction model, query manager, and the like.
[0080] Furthermore, while embodiments are described herein with
respect to a client-server model, this model is merely used for
purposes of illustration. Persons skilled in the art will recognize
other communication paradigms, all of which are contemplated as
embodiments of the present invention. Indeed, as pointed out above,
the server computers 102 may in fact be related as peers, rather
than computers of in a client-server paradigm. Further, even
assuming a client-server model, a given computer may behave as
either a client or a server at different times, depending on the
context. As such, the terms "client" and "server" are not to be
taken as limiting.
[0081] FIG. 6 illustrates another system 600 according to an
embodiment of the invention. System 600 may include at least one
client computer 101 and a plurality of servers 102, as illustrated
in FIG. 6. As illustrated, the client computer 101 may be coupled
with a server 102a. The server 102a may be coupled with a server
102b via a first P2P network 190, and server 102b may be coupled to
the servers 102c and 102d via a second P2P network 191.
[0082] As illustrated in FIG. 6, an abstract query 510 may be sent
from the client computer 510 to the server 102a. Server 102a may
send the abstract query to server 102b via the network 190, as
discussed above. The server 102b may retrieve results for the
abstract query 510, for example, by converting the abstract query
510 to a local query, as discussed above. In addition, the query
program 244b of the server 102b may transfer the query 510 to one
or more other peers 102c and 102d via the P2P network 191 to
retrieve further results for the query 510. For example, server
102b may include a record including a list of peer servers
associated with the server 102b. Accordingly, query program 244b
may access the record to determine its peer servers, and send the
abstract query 510 to one or more of the peers listed in the
record.
[0083] The server 102b may receive the results from the servers
102c and 102d via network 191, and combine the results with results
from the server 102b before sending the results to the server 102a
via the network 190. In an alternative embodiment, the server 102b
may transfer its own results to the server 102a via network 190,
and then subsequently transfer the results from servers 102c and
102d to the server 102a as they are received.
[0084] In some embodiments, each of servers 102c and 102d may be
coupled with one or more other networks not shown in FIG. 6.
Accordingly, the servers 102c and 102d may continue to send the
query 510 to respective peers via the one or more other networks
such that the query 510 cascades through multiple networks and
multiple servers 102 to retrieve a comprehensive and complete set
of results fro the query 510.
[0085] The transfer of an abstract query from one server 102 to one
or more other servers 102 over a network, for example, networks 190
and 191, is referred to herein as a "network hop". In one
embodiment of the invention, a server 102 or client 101 initiating
transfer of an abstract query 510 to one or more other servers 102
may be configured to define a maximum network hops for the abstract
query. For example, if the maximum hop for the query is set to 1,
the abstract query 510 may only be sent from the server 102a to the
server 102b via the network 190 (i.e. one network hop), but may not
be sent from the server 102b to the servers 102c and 102d.
[0086] In one embodiment, the abstract query 510 may include the
maximum hop value encoded therein. Furthermore, the abstract query
510 may also include a current number of hops encoded therein. Each
server 102 may be configured to update the current hop value
encoded in the abstract query 510 before sending the abstract query
510 to one or more other servers 102 via a P2P network. If a server
102 receives an abstract query 510 wherein the maximum hop value is
equal to the current hop value, the server 102 may not send the
query to any further servers 102.
[0087] In some embodiments, a server 102 may be coupled with
multiple P2P networks. Therefore, it is possible that the server
102 may receive the same query 510 from each of the multiple P2P
networks. However, providing query results each time the abstract
query is received may result in a requesting client computer 101 or
server 102 receiving duplicate copies of the query results.
Therefore, in one embodiment of the invention, the query 510 may
include a unique query ID encoded therein. Therefore, if a server
102 receives an abstract query having the same query ID as a
previously received abstract query, the server 102 may simply
ignore the abstract query or explicitly signal to the sending
server that no action will be taken.
[0088] FIG. 7 is a flow diagram of exemplary operations performed
by a query manager 244 according to an embodiment of the invention.
The operations may begin in step 710 by receiving an abstract
query. The abstract query may be received from a client computer
101 or an application 240 of a first server 102. Furthermore, the
received abstract query may contain logical fields defined
according to a first data abstraction model associated with the
first server 102.
[0089] In step 720 the query manager 244 may issue the abstract
query against a database associated with the first server 102 and
receive query results. In step 730, the query manager 244 may send
the abstract query to one or more second servers 102 via a network.
The query manager may then receive results from the abstract query
from one or more of the second servers 102 via the network in step
740. In step 750, the query manager 244 may provide the results
received from the first server and one or more second servers to
the requesting client computer or application 240.
[0090] FIG. 8 is a flow diagram of exemplary operations performed
by a query manager 244 according to another embodiment of the
invention. The operations may begin in step 810 by receiving an
abstract query including one or more logical fields defined by a
first data abstraction model. In step 820, the query manager 244
may convert the received abstract query to a local abstract query
including logical fields defined by a second data abstraction
model.
[0091] Converting the received abstract query to a local abstract
query may involve determining concept codes associated with each of
the logical fields associated with the received abstract query. The
concept codes may be, in one embodiment, received with the abstract
query. The query manager 244 may identify logical fields in the
second data abstraction model associated with the concept codes and
generate the local abstract query based on the identified logical
fields. In step 830, the query manager 244 may issue the local
abstract query against a local database to retrieve query results.
In step 840, the query manager may provide the query results to a
requesting server 102 or client 101.
NOTIFICATION OF AVAILABLE QUERY AUGMENTATION WITHIN QUERY
RESULTS
[0092] In some cases an abstract query received by a server 102 may
contain one or more logical fields with concept codes that do not
have corresponding logical fields in a local data abstraction
model. For example, the exemplary abstract query 510 includes a
logical field "Last Name". As illustrated in FIG. 4, the logical
field "Last Name" may have a concept code 101. It is possible that
one or more of the servers 102 (see FIG. 5) may not have a logical
field corresponding to the concept code 101 in their respective
data abstraction model.
[0093] For example, data abstraction model 248d of server 102d (see
FIG. 5) may not have a logical field that is associated with
concept code 101. Therefore, the server 102d may not be able to
provide results for the abstract query 510 because, as illustrated
in the exemplary query above, the logical field "Last Name" is a
part of the query condition.
[0094] While it is possible that a particular server 102 may not
have logical fields in their respective data abstraction models
that are associated with a specifically identified concept code, it
may be possible that the server 102 contains logical fields
associated with related concepts. For example, in one embodiment,
the query 510 may include a logical field "Felines" with a concept
code 676. The server 102d may not contain any logical fields
associated with the concept code 676 in the data abstraction model
248d. However, the data abstraction model 248d may include a
logical field "Tigers" with a concept code 677. Because "Tigers"
are a type of "Felines", the data associated with the logical field
"Tigers" may be relevant to the query. Accordingly, retrieving data
associated with a logical field of a related concept may be
desirable.
[0095] In some cases, even if the logical field "Felines"
associated with the concept code 676 is found, it may be desirable
to notify the user of the existence of the logical field "Tigers"
associated with concept code 677. By providing such notification,
the user may be able to create a more robust query to extract
desired results. For example, the user may modify the abstract
query 510 to include the logical field "Tigers". The modified
abstract query 510 may retrieve additional desired results from
server 102d.
[0096] In some embodiments of the invention, providing query
results may include providing, along with the query results,
metadata associated with concepts related to the concepts
identified in the abstract query. By providing such metadata, a
user or application may be able to reposition the query to retrieve
results from logical fields associated with the related concepts.
Alternatively, in some embodiments, a server 102 receiving a query
may be configured to automatically reposition the query to retrieve
results for logical fields associated with related concepts.
Repositioning the query, as described herein, may generally involve
changing, adding, subtracting, or otherwise modifying the query
and/or query conditions so that the modified query retrieves a
different set of results.
[0097] Any number of methods for identifying related concepts is
contemplated. For example, in some embodiments concepts may have
predefined relations to one another. For example, a first concept
may be defined as a synonym of a second concept. Alternatively, the
first concept may be defined as a type, use, or the like, of the
second concept. In a particular embodiment, the concepts may have
predefined relations to one another as defined by a hierarchical
structure such as, for example, a data tree, wherein a position of
the concept in the data tree relative to one or more other concepts
defines the relationship between the concepts. In some embodiments,
the relationship between concepts may be derived from a recognized
universal industry standard. For example, Medical Subject Headings
(MeSH) includes medical terminology known as descriptors arranged
in a hierarchical manner.
[0098] FIG. 9 illustrates an exemplary structure 900 defining
relationships between a plurality of concepts A-E. In one
embodiment, the structure 900 may be defined within the data
abstraction model of each server 102a-d. For example, Concept B is
defined as a synonym of Concept A. In one embodiment of the
invention, if a first concept is a synonym of a second concept
identified in a received abstract query, metadata regarding the
first concept may be sent back to the requesting entity. For
example, a description of the concept (such as the concept name)
and concept code may be sent to the requesting entity along with
the query result. In some embodiments, the metadata may include
logical field names and definitions associated with the related
concepts.
[0099] In an alternative embodiment, if a first concept is synonym
of a second concept identified in a received abstract query, a
logical field associated with the second concept may be used to
generate a local query. For example, the query 510 in FIG. 5 may
include a logical field associated with Concept A. The data
abstraction model 248d of server 102d may include one or more
logical fields associated with Concept B, but no logical fields
associated with Concept A. Because Concept B is a synonym of
Concept A, the query manager 244d may simply use the logical fields
associated with Concept B to compose a local abstract query to
retrieve results for the abstract query 510, even though the
concept codes for Concept A and Concept B are different.
[0100] Referring back to FIG. 9, Concept C is defined as a type of
Concept A in the structure 900. In other words, Concept C may be a
subset of Concept A. For example, as discussed above, "Tigers" are
a type of "Felines". Also illustrated in FIG. 9 is Concept D, which
is defined as a use of Concept A. For example, "Integrated
Circuits" may be a use related to "Silicon". As with synonyms, in
one embodiment, metadata regarding concepts identified as types or
uses may be sent to a requesting entity along with query results.
Alternatively, a query program 244 may generate a local query based
on logical fields associated with concepts that are types or uses
of concepts identified in a received query 510.
[0101] While synonyms, types and uses are described herein as means
for determining related concepts, in alternative embodiments, any
other reasonable means for determining relationship between
concepts may be used. For example, in some embodiments the relative
position of the concepts in the hierarchical structure 900 may
determine whether concepts are related. For example, FIG. 9
illustrates a Concept E which is defined as a type of Concept D. In
some embodiments, related concepts for any particular concept may
include concepts that are a predetermined number of levels from the
concept. For example, if a threshold of 1 is used, Concept C may be
a related to Concept A but Concept D will not be related to Concept
A.
[0102] FIG. 10 is a flow diagram of exemplary operations performed
by a query manager 244 according to an embodiment of the invention.
The operations may begin in step 1010 by receiving an abstract
query including one or more logical fields defined by a first data
abstraction model and a concept code associated with each of the
one or more logical fields. In step 1020, the query manager 244 may
determine whether a local data abstraction model has concept codes
related to the received concept codes. For example, in one
embodiment, to determine related concepts, query manager 244 may
reference a data structure such as, the data structure 900
described above with respect to FIG. 9. If related concept codes
are found, the query manager may be configured to provide metadata
related to the related concept codes to a requesting entity.
[0103] Alternatively, in some embodiments, the query manager 244
may generate a local abstract query based on logical fields
associated with one or more received concept codes and one or more
related concept codes. The local abstract query may be issued
against a local database to retrieve query results, which may be
provided to the requesting entity.
AUGMENTING LOCAL DATA ABSTRACTION MODELS WITH LOGICAL FIELDS FROM
PEERS
[0104] The data abstraction models 248a-d illustrated in FIG. 5 may
each be different, including respective distinct logical fields.
Therefore, the logical fields of abstract query 510 which may be
based on data abstraction model 248a, may be significantly
different than logical fields in data abstraction models 248b-d.
However, access to the distinct logical fields in data abstraction
models 248b-d may be desirable while composing the abstract query
510 because the distinct logical fields may contain desired
data.
[0105] It may be possible that distinct logical fields in different
servers 102 refer to the same concept. For example, data
abstraction model 248a of server 102a may include a logical field
"Desktops" that is defined by a concept code associated with
"computers". Data abstraction model 248b of server 102b may include
a logical field "Laptops" that is also defined by the concept code
associated with "computers". Because the data abstraction model
248a only includes the logical field "Desktops", query 510 may be
limited to that particular logical field. However, the logical
field "Laptops" may also be desirable while composing query 510
because desktops and laptops are both associated with the same
concept, i.e., computers.
[0106] In one embodiment of the invention, the query managers
244a-d of each of servers 102a-d may be configured to identify
distinct logical fields in each others' data abstraction models
248a-d, and copy the distinct logical fields into a respective
local data abstraction model. For example, query manager 244a may
be configured to identify distinct logical fields in the data
abstraction models 248b-d and copy the distinct logical fields into
the data abstraction model 248a. Therefore, the distinct logical
fields may be available for composing the query 510.
[0107] In one embodiment, identifying the distinct logical fields
to be copied may involve determining distinct logical fields that
have the same concept code as a logical field in a local data
abstraction model. For example, query manager 248a may determine
that the logical field "Laptops" in the data abstraction model 248b
has the same concept code as the logical field "Desktops" in the
local data abstraction model 248a. Therefore, the logical field
"Laptops" may be copied into the data abstraction model 248a. In
some embodiments, the query manager 244 may also be configured to
copy logical fields associated with concepts related to a concept
of a local logical field. Determining related concepts is described
in greater detail in the previous section.
[0108] While logical fields from one or more peer servers 102 may
be copied into a local data abstraction model, the copied logical
fields may not map to physical fields in a local database. This may
be because there may be no physical data corresponding to the
copied logical field in the server 102. Therefore, queries composed
using the copied logical fields and issued against the local
database may fail. However, the query may still be transferred to
peer servers 102 to retrieve query results therefrom. For example,
if the abstract query 510 is composed with the logical field
"Laptops" copied from data abstraction model 248b, the abstract
query may fail to retrieve results if issued against a database at
server 102a because there may be no physical data corresponding to
the copied logical field "Laptops" in server 102a. However, the
abstract query 510 may be transferred, as described above, to the
server 102b via the network 190 by the query manager 244a, from
where query results may be retrieved.
[0109] In one embodiment of the invention, the query manager 244
may be configured to periodically seek distinct logical fields as
described above from data abstraction models in peer servers 102.
In alternative embodiments, the distinct logical fields may be
discovered during interaction between the servers 102. For example,
as described in the previous section, the servers 102 may be
configured to transfer metadata regarding concepts, concept codes,
and logical fields to each other in response to receiving an
abstract query. The metadata may be analyzed to determine whether
distinct desirable logical fields exist in peer servers 102.
[0110] In one embodiment of the invention, the query manager 244
may be configured to periodically validate logical fields in a
local data abstraction model 248. For example, query manager 244a
may verify that a copied logical field in data abstraction model
248a still exists in a foreign data abstraction model, for example,
data abstraction model 248b, from which the logical field was
copied. If the copied logical field no longer exists in the foreign
data abstraction model, the query manager may be configured to
remove the copied logical field from the local data abstraction
model.
CONCLUSION
[0111] By providing a means for converting an abstract query
containing logical fields defined in a first data abstraction model
to an abstract query containing logical fields defined in a second
data abstraction model based on concept codes associated with the
logical fields, embodiments of the invention allow query results to
be retrieved from multiple independent systems more
efficiently.
[0112] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
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